Sections of this somewhat longish post are ordered from the perspective of science fiction fans; if you are not one, interesting stuff may be down below rather than early in the post.

Mapping magnetic anomalies.

The Martian Chronicles on a Swedish instrument called SARA on board the ship: "SARA will also be able to study magnetic anomalies, presumably because the magnetic fields will change how the solar wind interacts with the surface."

"Magnetic anomaly" caught my attention because this is what begins the fuss in Arthur Clarke's famous novel "2001 A Space Odyssey". TMA it was called in the story - Tycho Magnetic Anomaly, because it was found in the Tycho region.

Radioactive mapping is one of the things the mission will do. But what is it? And why do it?

The Martian Chronicles clarifies the purpose of the on board Bulgarian instrument that will do this job: "The whole goal is for this thing to get bombarded with radiation and see how much there is, what range of energies the particles have, and figure out how that dose might change for different locations on the moon. The Apollo astronauts were only out of Earth’s protective magnetic field for a few days, but for colonists spending months or years out there, it’s important to know how much radiation shielding they will need, and what type of radiation is the most dangerous."

Detecting water ice.

The Martian Chronicles on an on board Indian instrument called HEX: "a thick ice deposit would absorb x-rays that normally would be emitted to space, so by measuring changes in x-ray emission, HEX might be able to detect water ice."

Why this multistage trajectory? Answer is, primarily, caution: "We could have done it [in] one shot, but there is a possibility of missing the moon. So we have adopted an incremental increase in the orbits’ perigee." I suppose "apogee" is meant, & "perigee" is a misquote.

Also, "There will be a need to correct the orbit once in two weeks to maintain a 100 km circular orbit" on moon. I guess at the end of its useful life - meaning propellant & fuel exhausted - it will simply fall somewhere on moon?Related: Arthur Clarke's novel "Islands in the Sky" lightly touches upon the subject of human littering in space. A habit now when it doesn't cause much damage but a costly danger when space travel becomes common (because habits die hard). Not that ISRO is alone - everyone traveling to space seems to be doing it today.

Mr Annadurai answers several other questions too, including why fire at perigee & how moon capture will happen.

A related point: Reducing the speed - needed for capture by moon & lowering of orbit there - requires that "the orientation of the spacecraft is reversed — turned 180 degrees". This implies the craft is fitted with special orientation rockets that can fire simultaneously in more than one directions. I'd not thought of it; I guess it's needed by all craft that orbit earth too.

I'm puzzled why they published pictures of Australia rather than India. I assume it was engineering considerations, rather than oversight.

"The camera can take black and white pictures of an object" & "has a resolution of about 5 metres." I suppose they meant 5m from a distance of 100 km, the target lunar orbit, & that earth pictures being distributed were at far lower resolution?

I assume he meant it for part of the moon visible from Chandrayaan-1 orbit around it. I mean - it cannot see "the whole moon" from a single orbit. Or do they intend to change orbits during its 2 year duty?

Gossip: Chandrayaan-3 (manned landing in 2015).

I seem to have misplaced a juicy quote from some babu or neta in Delhi that gave me a smile. It appeared in a local newspaper a few days back - I think Indian Express, but I'm not sure.

I interpreted the long winded quote as saying that: Delhi was upset that Chandrayaan-3 was announced publicly by ISRO bosses, & didn't let the neta concerned get publicity! He clarified that the project is not likely to be killed for lack of budget.

Related older report: G Madhavan Nair, Chairman of ISRO: "We are planning to carry two human beings into the space in our first manned space mission... The project outlay is Rs 120 billion".

What next?

All moon posts, including fiction set on moon. A-rated stories probably won't disappoint. For free fiction, search for "full text" (without quotes). Or browse through all free fiction posts, including stories unrelated to moon.

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comments:

"I assume he meant it for part of the moon visible from Chandrayaan-1 orbit around it. I mean - it cannot see "the whole moon" from a single orbit. Or do they intend to change orbits during its 2 year duty?"

I think he meant the whole moon, but not all at once. Chandrayaan will probably be put into a polar orbit, which is what is usually used for global mapping. You just let the planet rotate while the spacecraft's orbit remains "fixed" in space, so each orbit you pass over new ground.